Follicular cyst in a patient with myotonic dystrophy: a case of cyst with differentiation toward follicular infundibulum, isthmus, inner root sheath, and hair

Multiple Follicular Hybrid Tumors Presenting in Association With Myotonic Dystrophy Type 1

ABSTRACT

Follicular hybrid cysts are uncommon entities derived from 2 or more components of the folliculo-sebaceous-apocrine unit. The pathogenesis of follicular hybrid cysts is uncertain; however, they are proposed to derive from the multipotent nature of follicular stem cells. Myotonic dystrophy type 1 is an inherited muscular dystrophy caused by an unstable trinucleotide repeat expansion in the myotonic dystrophy protein kinase gene, notably associated with multiple pilomatricomas. We report a novel case of multiple follicular hybrid tumors presenting in association with myotonic dystrophy type 1. We suspect that multipotent follicular stem cells, under the influence of the hypermutability phenotype present in myotonic dystrophy type 1, contributed to the pathogenesis of multiple follicular hybrid tumors in our patient.

Skin features in myotonic dystrophy type 1: an observational study

Poor data regarding skin involvement in Myotonic Dystrophy, also named Dystrophia Myotonica type 1, have been reported. This study aimed to investigate the prevalence and types of skin disorders in adult patients with Myotonic Dystrophy type 1. Fifty-five patients and one hundred age- and sex-matched healthy subjects were referred to a trained dermatologist for a complete skin examination to check for potential cutaneous hallmarks of disease. No difference in prevalence of preneoplastic, neoplastic, and cutaneous lesions was detected between the two groups. Among morphofunctional, proliferative and inflammatory lesions, focal hyperhidrosis (p < 0.0001), follicular hyperkeratosis (p = 0.0003), early androgenic alopecia (p = 0.01), nail pitting (p = 0.003), pedunculus fibromas (p = 0. 01), twisted hair (p = 0.01), seborrheic dermatitis (p = 0.02), macules of hyperpigmentation (p = 0.03) were significantly more frequent in patients compared with controls. In patients with Myotonic Dystrophy type 1 significant differences according to sex were found for: early androgenic alopecia, twisted hair and seborrheic dermatitis, whose prevalence was higher in males (p < 0.0001). Our preliminary results seem to rule out an increased prevalence of pre-neoplastic, and neoplastic skin lesions in Myotonic Dystrophy type 1. On the other hand, an increased prevalence of morphofunctional, inflammatory, and proliferative diseases involving adnexal structures seems to characterize adult patients with Myotonic Dystrophy type 1.

Hypothesis: neoplasms in myotonic dystrophy

Tumorigenesis is a multi-step process due to an accumulation of genetic mutations in multiple genes in diverse pathways which ultimately lead to loss of control over cell growth. It is well known that inheritance of rare germline mutations in genes involved in tumorigenesis pathways confer high lifetime risk of neoplasia in affected individuals. Furthermore, a substantial number of multiple malformation syndromes include cancer susceptibility in their phenotype. Studies of the mechanisms underlying these inherited syndromes have added to the understanding of both normal development and the pathophysiology of carcinogenesis. Myotonic dystrophy (DM) represents a group of autosomal dominant, multisystemic diseases that share the clinical features of myotonia, muscle weakness, and early-onset cataracts. Myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2) result from unstable nucleotide repeat expansions in their respective genes. There have been multiple reports of tumors in individuals with DM, most commonly benign calcifying cutaneous tumors known as pilomatricomas. We provide a summary of the tumors reported in DM and a hypothesis for a possible mechanism of tumorigenesis. We hope to stimulate further study into the potential role of DM genes in tumorigenesis, and help define DM pathogenesis, and facilitate developing novel treatment modalities.